// filters walks the where clause of a select statement and returns a map with all series ids
// matching the where clause and any filter expression that should be applied to each
func (m *Measurement) filters(condition influxql.Expr) (map[uint64]influxql.Expr, error) {
if condition == nil || influxql.OnlyTimeExpr(condition) {
seriesIdsToExpr := make(map[uint64]influxql.Expr, len(m.seriesIDs))
for _, id := range m.seriesIDs {
seriesIdsToExpr[id] = nil
}
return seriesIdsToExpr, nil
}
ids, seriesIdsToExpr, err := m.walkWhereForSeriesIds(condition)
if err != nil {
return nil, err
}
// Ensure every id is in the map and replace literal true expressions with
// nil so the engine doesn't waste time evaluating them.
for _, id := range ids {
if expr, ok := seriesIdsToExpr[id]; !ok {
seriesIdsToExpr[id] = nil
} else if b, ok := expr.(*influxql.BooleanLiteral); ok && b.Val {
seriesIdsToExpr[id] = nil
}
}
return seriesIdsToExpr, nil
}
// Ensure that we see if a where clause has only time limitations
func TestOnlyTimeExpr(t *testing.T) {
var tests = []struct {
stmt string
exp bool
}{
{
stmt: `SELECT value FROM myseries WHERE value > 1`,
exp: false,
},
{
stmt: `SELECT value FROM foo WHERE time >= '2000-01-01T00:00:05Z'`,
exp: true,
},
{
stmt: `SELECT value FROM foo WHERE time >= '2000-01-01T00:00:05Z' AND time < '2000-01-01T00:00:05Z'`,
exp: true,
},
{
stmt: `SELECT value FROM foo WHERE time >= '2000-01-01T00:00:05Z' AND asdf = 'bar'`,
exp: false,
},
{
stmt: `SELECT value FROM foo WHERE asdf = 'jkl' AND (time >= '2000-01-01T00:00:05Z' AND time < '2000-01-01T00:00:05Z')`,
exp: false,
},
}
for i, tt := range tests {
// Parse statement.
stmt, err := influxql.NewParser(strings.NewReader(tt.stmt)).ParseStatement()
if err != nil {
t.Fatalf("invalid statement: %q: %s", tt.stmt, err)
}
if influxql.OnlyTimeExpr(stmt.(*influxql.SelectStatement).Condition) != tt.exp {
t.Fatalf("%d. expected statement to return only time dimension to be %t: %s", i, tt.exp, tt.stmt)
}
}
}